Background: I received an .asc file with elevation data in southern Oregon. The horizontal datum = feet, vertical datum = MLLW. I edited the header, and successfully used the ASCII to Raster tool. I used the Define Projection tool to set projection. I tried:
I used the Project Raster to our working projection (WGS_1984_UTM_Zone_10N).
**All of these steps were conducted in ArcCatalog.**
I was told by .asc provider that:
"Use Oregon state plane South survey feet (id# 3602), because grid cells will have the same spacing in the latitudinal and longitudinal direction. You should be able to use this to load into arc and then convert to another datum (lat/lon)."
Problem: When I put it in ArcMap with a basemap in the WGS_1984_UTM_Zone_10N, it is offset. I tried estimating the offset and using the Shift tool, but it is difficult given the permanent features in a basemap with current bathymetry topography. It seemed to indicate the offset may not be quite the same everywhere. I'm not sure though.